Users of a social networking system may use the system to interact with each other based on content shared within the system. One topic of discussion might be a media item depicting two users together. In conventional systems a user needs to first search for and find a media item associated with a second user before starting a conversation in the context of the media item. For example, the user may be obliged to look through many photo albums to find a particular photo containing the second user before sending it to the user and starting a conversation about the photo. Thus, in many cases, users will not go to the effort to engage in these conversations, thereby missing opportunities for engaging with other users.